Pressure and vacuum relief valve.



D. CRAIG. PRESSURE AND VACUUM RELIEF VALVE.

APPLICATION FILED JULY 13. I914- Patented Oct. 16,1917.

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DAVID CRAIG, OF PEABODY, MASSACHUSETTS.

PRESSURE AND VACUUM RELIEF VALVE.

Specification of Letters Patent.

Patented Oct. 16, 191:1.

Application filed July 13, 1914. Serial No. 850,810.

To all whom it may concern:

Be it known that 1, DAVID CRAIG, a citizen of the United States, andresident of Peabody, county of Essex, Commonwealth of Massachusetts,have invented an Improvement in Pressure and Vacuum Relief Valves, ofwhich the following description, in connection with the accompanyingdrawings, is a specification, like characters on the drawingsrepresenting like parts in each of the several views.

This invention relates to a relief valve device adapted for use withfluid containers and pressure systems, and is particularly, though notexclusively, designed for domes tic boiler installations. A prime objectof the invention is to provide a simple, compact, unitary valve deviceadapted to relieve the boiler and system of eiicessive or dangerouspressure, and also to protect and relieve the boiler from crushing orcrumpling in due to vacuum or unduly diminishing pressure. To these endsin the preferred embodiment shown, I provide a valve with provision forholding it to its seat with variable predetermined spring pressure andform said valve so as to serve also as a valve seat member for anothervalve adapted to control flow of fluid in the opposite direction. Theabove and other objects and features of the invention will be betterunderstood from the following detailed description taken in connectionwith the accompanying drawings and will be thereafter pointed out intheappended claim.

Referring to the drawings:

Figure 1 is an elevation showing my improved device applied to a pipeconnection that may communicate with a boiler; and

Fig. 2 is a central vertical section through my improved valve, thecentral smaller valve and the spring being shown in elevation.

A barrel housing is indicated at 10 with a threaded nipple 11 at one endto engage with a pipe connection such as one branch 12 of a T, while theother end of the barrel has a long threaded nipple 13 to which is fittedan adjustable cap 14. The passage through the barrel is reduced at oneend, shown as through the nipple 11 as seen at 15 and where this reducedportion begins it is beveled off to form a valve seat 16 to which isfitted a plug valve 17 This valve is yieldingly pressed to its seat witha predetermined variable pressure by a coil spring 18 having backingagainst the cap 14. Thus by adjusting said cap the tension of the springmay be varied and hence the point at which the valve 17 will open torelieve excess pressure can be varied and set as required. The valve 17has a reduced neck 19 extending through the reduced passage 15 withclearance and a central passage 20 extends through this valve and itsneck. This passage is controlled by a valve 21 fitted to a seat 22 onthe end of the neck 19 and equipped with a long stem 23 extendingthrough the passage 20 with clearance and as shown most of the waythrough the barrel 10; thus serving to guide and steady the action ofthe valve 21. The cap 14 is provided with a port 24 to permit passage ofthe fluid in either direction. In practice the active face of valve 21is preferably made of lead and as the valve 17 with its neck 19 areusually of brass, there is no likelihood or danger of the cementing orstickin of the valve to its seat. It is also to be noted that the neck19 of valve 17 and the valve 21 thereon extend up some little distanceabove the end of the nipple 11. The branch 12 of the T connection isalso made relatively short as shown and in this way the valve 21 and itsseat 22 extend up into the current of flowing water so that they arekept clean and free from sediment.

Thus the valve 17 is adapted to guard the system from excess pressure byproper adjustment of the cap 14 according to the conditions of servicewhile the valve 21 will at once open freely as soon as the pressure inthe system drops materially below atmospheric pressure relieving theboiler from danger of buckling or crumpling in from partial vacuum. I amaware that the invention can be embodied in other specific forms withoutdeparting from the spirit of the invention and I therefore refer to the.appended claim rather than to the foregoing description to indicate thescope of the invention.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

A combined pressure and vacuum relief valve, comprising a barrel housinghaving a reduced portion formed with an internal tapering seat at oneend portion thereof and externally threaded at the other end thereof, acap fitted to the last named end of said housing with a central holetherethrough, plug valve to close the passage therethrough, a plug valvehaving a larger inner end having an elongated stem extending through 15oosely fitting the interior of said housing the passage of said plugvalve, the end of With a smaller outer end projecting outward saidhousing to Which said plug valve is 5 a substantial distance beyond theend or" said fitted being externally threaded for fitting housing, andWith an intermediate conical to a pipe connection. portion constitutinga valve to fit said taper- In testimony whereof, l? have signed my 20ing seat in the housing, a spring reacting name to this specification,in the presence between said end cap of said housing and of twosubscribing Witnesses.

.10 thelargenend of said plug valve, said plug DAV 1D CRAIG.

valve havlnga central lengthwise passage Witnesses therethrough, and avalve fitting the pro C. L. ROGERS,

jecting end or" the smaller portion of said Louise A. JORDAN.

